The present invention relates to an assembly for scarifying soil, and particularly to a cutting head having a plurality of tine assemblies for use on a garden tiller or the like. More particularly, the present invention relates to a tine assembly including a rotary blade mounted on a rotable hub at a predetermined, nontransverse angle with respect to the axis of rotation of the hub so that the rotary blade oscillates from side to side upon rotation of the hub about its axis to cut a wider path through the soil than conventional tine assemblies.
Tillers or cultivators that are used to prepare soil for planting crops, grass, or other plants include tine assemblies which rotate to loosen the soil. It is desirable for the tiller to cut as wide a path as possible through the soil to reduce the number of passes necessary to prepare an area of ground for planting.
Attempts to increase the width of the path cut using a hand operated tiller by adding extra tine assemblies to the drive shaft of the tiller generally have not been effective. The number of tine assemblies which can be used in a hand operated tiller is limited because the addition of each tine assembly increases the force that must be exerted by an operator to control the tiller as it is pushed through a soil plot. Typically, a hand operated tiller includes between four and six tine assemblies for loosening the soil.
One method of increasing the width of ground that each rotary blade of the tine assembly cuts is to increase the length of the tines which extend away from each rotary blade. As the length of the tines increase, however, the likelihood that one of the tines will break during operation of the tiller also increases. It is therefore desirable to provide a tine assembly that will cut a wide path through the soil without increasing the length of the tines in order to minimize the problem of tine breakage.
One object of the present invention is to provide a tine assembly for cutting a wide path through the soil having tines of a short length selected to ensure that the tines will not generally break during normal operation of a tiller on which the tine assembly is mounted.
Another object of the present invention is to provide a tine assembly which is compatible with existing tiller assemblies so that the tine assembly can be used without modification of the existing tiller.
Yet another object of the present invention is to provide a tine assembly which digs, lifts, and recuts the soil to reduce the number of passes that must be made through the soil to prepare the soil for planting.
According to the present invention, a rotary blade for use on a drive shaft of a tiller comprises a central mounting region oriented in a first plane and a blade body portion oriented in a second plane skewed with respect to the mounting region. The blade body portion of the rotary blade oscillates from side to side in response to rotation of the drive shaft.
In a preferred embodiment of the present invention, a tine assembly is provided for use with a tiller assembly including a drive shaft having an axis of rotation. The tine assembly includes at least one rotary blade and means for mounting the at least one rotary blade to the drive shaft to align each rotary blade at a predetermined angle with respect to the axis of rotation. Upon rotation of the drive shaft each rotary blade oscillates from side to side to cut a wider path through the soil than rotary blades of conventional tine assemblies.
Each rotary blade is oriented to lie at an angle of about 5.degree. with respect to a plane perpendicularly transverse or normal to the axis of rotation of the rotary blade. The mounting means includes a hub configured to surround the drive shaft. The hub includes a face plate for coupling the rotary blade to the hub.
One feature of the present invention is the provision of a tine assembly having a rotary blade situated at an angle with respect to the axis of rotation of the drive shaft on which the tine assembly is mounted so that the rotary blade is not parallel to a plane normal to the axis of rotation. Advantageously, such a configuration causes side-to-side oscillation of the rotary blade along the axis of rotation as the tine assembly is rotated. This lateral oscillation of the rotary blade maximizes the width of soil that the blade cuts and minimizes the length of the tines that extend away from the blade. Accordingly, the tine assembly is designed to cut a wider path through the soil than existing tine assemblies which can be mounted on existing tillers without modifying the existing tiller. Advantageously, the tine assemblies of the present invention are configured to be used on most existing tillers without the added cost of altering the tiller.
Yet another feature of the invention is the provision of a uniform, symmetrically shaped rotary blade which can be mounted on a hub in several selected orientations so that the angle of the rotary blade with respect to the longitudinal axis of the hub can be readily changed. Advantageously, such a symmetrical configuration permits an operator of the tiller to stock only one type of rotary blade for replacement purposes in case of breakage. In addition, production costs for the rotary blades are reduced because there is no need to produce several styles of the rotary blades in order to permit the rotary blades to be mounted in various orientations. Thus, a single machine can produce a rotary blade which can be mounted at any desired orientation on the tiller.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.